The chronology of the flood is summarised in Table 1.

After 40 days the rains stopped but the flood level remained high for another 110 days making 150 days in all. See ch7v24. And the waters prevailed upon the earth an hundred and fifty days. The state of the flood during the period of 110 days after the rains ceased is described in ch8v1 to 3 This is not an easy to passage to interpret but it seems that after the rains stopped and a drying wind commenced the waters assuaged. Ch8v1. This means the flood level stopped rising violently. It rose more and more slowly. As the wind continued to blow the waters returned from off the earth continually. Ch8v3. This is a poor translation owing to the Hebrew scholar's poor understanding of floods! The literal meaning of this phrase is that the waters were, 'going and returning'. Floodwater was being removed from the Euphrates basin by evaporation and natural drainage but floodwater was still being discharged into the basin by numerous mountain tributaries. There is always a considerable time lag between the end of torrential rain and the arrival of flood water to the main river from the longer tributaries. Eventually the discharge of the tributaries to the Tigris and Euphrates declined and the great flood level began to drop slowly. After 110 days of high water Noah knew that the waters were abated Ch8v3. or dropping because the ark grounded on high land.(Mts of Ararat) It is probable that the maximum height of the flood was reached at the mid point of the 110 day period - 95 days from the commencement of the rains.

There is absolutely no doubt so far that the description of the flood is of a natural one of regional dimensions. The flood is behaving like a natural one such as is experienced today. The record of the subsidence of the waters confirms the event as a local one.

We have a crucial piece of information in vs4 and 5. And the ark rested in the seventh month, on the seventeenth day of the month, upon the mountains of Ararat. And the waters decreased continually until the tenth month; in the tenth month, on the first day of the month, were the tops of the mountains seen. Now the rains began on seventeenth day of the second month. So 5 months is the same as 150 days. This makes a month 30 days in length. So the length of time from the ark coming to rest on higher land and the emergence of this higher land was 74 days. The smallest fall in level possible in those 74 days is the draught of the ark - 7 metres. It cannot be less. This gives us the rate of fall in the flood level - about 9 cms a day. If we assume this rate of fall took place from the 95th day to the end of the flood on the 314th day we can construct a graph to work out the maximum depth of the flood. (The rate of fall would not be constant, as I have indicated, but nevertheless this does give us another way of calculating the approximated maximum depth) See Diagram 1 It is clear that depth of the flood calculated in this way is entirely compatible with the depth of the flood deduced from the earlier description of the rise of the waters. However I can almost hear someone objecting. The rate of fall of flood level would have been much greater if the land the ark came to rest on was much higher than the surrounding hills. This would actually be very unlikely in even a genuinely mountainous area because the highest summits tend to be of much the same height. The account itself strongly suggests that the high land the ark came to rest upon was much the same height as the first high ground that was visible as the waters receded. If the first summits to emerge from the waters were much lower than the land on which the ark rested Noah would have known it was safe to leave the ark after 40 days had elapsed. As it was 40 days after the ark came to rest Noah was still in the ark contemplating experiments with a crow and a dove. By the time the dove was released vast tracts of land around the ark would have been free from water. The dove would have found plenty of places to rest the sole of her foot.v9. Noah's difficulty in judging the depth of the water around the ark suggests the hills that emerged were all much the same in altitude, terrace like, and not much different in height to the land the ark was resting upon.

The ark is at rest, probably on a flat terrace 14 metres or so above the surface upon which the ark was built. Noah can see hills poking above the floodwater in the distance. However he is not sure about the level of the floodwater around the door of his refuge and he is very reluctant to leave the safety of the ark. So after 264 days from the onset of the rains he releases a crow and a dove. The dove returns because it could find no roosting place but the crow does not return. This suggests that the land around the ark was a treeless expanse of soft wet mud. These are conditions that a carrion crow is well suited to - but not a dove.

After another 7 days olive trees made their appearance. They were growing from a lower level than the one the ark came to rest upon. I think it probable that in an area with an annual rainfall of 120 to 150mms olives would only grow on the floodplains of rivers where the water table was near the surface. Olives growing on the floodplain would not grow above 10 metres in height. The tops of the olives would start to emerge when the flood level dropped to say 8 metres above the floodplain. Possibly the dove returned with old olive leaves that remained on the tree beneath the floodwaters. Alternatively, olive branches were broken off the trees by floodwaters and buried in the silt of low terraces fringing the floodplain. Olives are propagated by burying branches in shallow trenches. Suckers are thrown up from the branches very rapidly. Maybe the leaves were growing on suckers thrown up from branches buried in the flood deposits.

If the olives were growing on a floodplain of much the same height as the one on which the ark stood before the flood then the flood waters fell through about 7 or 8 metres during the last 43 days. The rate of fall has increased. This was to be expected as the tributaries of the Tigris and Euphrates resumed their normal flow, or even less than their normal flow, due to the influence of the drying wind.

The fluctuation of flood level through time which is known as the flood hydrograph is shown in Diagram 2